NBL1 (Noggin-like, DAN family BMP antagonist) is a secreted protein that functions as a negative regulator of bone morphogenetic protein (BMP) signaling. NBL1 specifically antagonizes BMP2 and BMP4 signaling through receptor ligand activity, forming noncovalently linked homodimers that are generated in a cell-type-specific manner 1. The protein is involved in nervous system development, neuron differentiation, and morphogenesis [GO annotations], with its gene located at chromosome 1.11-p36.13, a region linked to neuroblastoma genesis and progression 2. Mechanistically, NBL1 inhibits both canonical (phospho-Smad1/5) and non-canonical (phospho-p38) BMP signaling pathways 3. NBL1 expression is regulated by gonadotropins and oocyte-derived factors like GDF9, suggesting roles in folliculogenesis and reproductive biology 1. Recent studies demonstrate NBL1's anti-fibrotic and anti-scarring properties; corneal treatment with NBL1 facilitated wound re-epithelialization and significantly reduced fibrosis without immune suppression 3. In disease contexts, NBL1 functions as a tumor suppressor. Hypermethylation of the NBL1 gene in ovarian cancer correlates with reduced mRNA expression and lower tumor suppressor function 4. In esophageal cancer, miR-1301-3p promotes invasion, migration, and EMT progression by downregulating NBL1 expression, with low NBL1 levels associated with poor prognosis 5. Additionally, NBL1 upregulation in mesenchymal stem cell-derived exosomes inhibits hypoxia-induced pulmonary vascular remodeling by modulating TGF-β1/Smad2/3 signaling 6.